Summary

The enclosed abstract was presented at the 13th Journées cancéropole Grand Sud-Ouest at Poitiers. The abstract Hafnium oxide nanoparticles as an emergent promising treatment for solid tumors describes how hafnium oxide nanoparticles were designed at the nanoscale in the form of crystalline 50nm-particles to efficiently absorb ionizing radiation and increase the radiation dose deposited – “hot spots” of energy deposit – from within the tumor cells for efficient cell killing.

Hafnium oxide nanoparticles (NBTXR3), administered as a single intratumoral injection and activated by radiotherapy, is currently evaluated in a phase II/III clinical trial in soft tissue sarcoma (STS) [NCT02379845], and in phase I/II clinical trials for head and neck [NCT01946867], prostate [NCT02805894], liver [NCT02721056; NCT02721056] and rectum cancers [NCT02465593]. So far, patients treated with NBTXR3 received radiotherapy as planned and showed a very good local safety profile.

Summary

Background: Soft tissue sarcoma (STS) is a large and heterogeneous group of malignant mesenchymal neoplasms characterized by a strong tendency toward local recurrence and metastatic spreading. Consistently, the immune microenvironment in sarcomas is highly variable. A new class of material with high electron density, hafnium oxide, was designed at the nanoscale to efficiently absorb ionizing radiation from within the tumor cells and augment the dose deposited to a tumor. […]

Material and Methods: Tumor tissues pre- (biopsy) and post-treatment (resection) are collected from patients with locally advanced STS (NCT02379845), who received either HfO2-NP activated by RT or RT alone. Immunohistochemistry and Digital Pathology for immune biomarkers and Pan-Immune gene expression profiling are analyzed.

Results: A significant increase of CD8+ T cells and a marked increase of CD3+ and PD-1 T cells and CD103+ immune cell infiltration post- vs pre-treatment are observed for HfO2-NP + RT while not differences are seen for RT alone (more than 10 patients analyzed in each arm). Functional analysis of genes expression up-regulated in HfO2-NP + RT post- vs pre-treatment shows an enrichment of cytokine activity (IL7, IFNA, IL11, IFNG), adaptive immunity (RAG1, TAP1, TAP2, TBX21, IFNG, LTK, CD37, CD22) and T cell receptor signaling pathway (CD28, CTLA4, CD274, BTLA, TIGIT, CD5, ZAP70) when compared to RT.

Conclusions: Promising results are observed in patients who received HfO2-NP + RT in terms of immune cells infiltration post- vs pre-treatment when compared to RT. […]

Summary

Background: Radiation therapy (RT) has demonstrated ability to augment antitumor immunity, promoting immunogenic cell death (ICD) and stimulating immune adjuvant effects. On the other hand, RT has also been reported to induce immunosuppressive responses. A new class of material with high electron density, hafnium oxide, was designed at the nanoscale (HfO2-NP) to efficiently absorb ionizing radiation and augment the radiation dose
deposited from within the tumor cells. […]

Methods: The potential ability of HfO2-NP exposed to RT to transform tumors into immunologically active lesions was tested in vitro and in vivo. In vitro, the level of ICD markers was evaluated in a panel of human cancer cell lines, following cells treated or not with HfO2-NP and irradiated. In vivo, a vaccination assay was performed to evaluate the host immune responses in immunocompetent mice inoculated with murine CT26 cancer cells treated or not with HfO2-NP and irradiated with 6 Gy. […]

Results: Higher DAMPs levels (cell surface expression of calreticulin, extracellular adenosine triphosphate level and extracellular high-mobility group box 1 level) were observed in the tested cancer cells treated with HfO2-NP + RT when compared to cancer cells exposed to RT. […]

Conclusions: These results suggest an efficient cell killing (ability to generate ICD) with superior potential of HfO2-NP + RT to transform the tumor into an effective in situ vaccine when compared to RT. Moreover, HfO2-NP treatment generates a marked increase of immune cells infiltration in the tumors suggesting that it may convert immunologically “cold” tumor into “hot” tumor and could be combined with immunotherapeutic agents across oncology.

Summary

Background: Hafnium oxide, an electron-dense material, was designed at the nanoscale to increase the radiation dose deposited from within the cancer cells: “Hot spot” of energy deposit where the nanoparticles are when exposed to radiation therapy (RT). Preclinical studies have demonstrated increase of cancer cells killing in vitro and marked antitumor efficacy in vivo with presence of these nanoparticles (HfO2-NP) exposed to RT, when compared to RT alone. […]

Material and Methods: CT26 (murine colorectal cancer cells) were subcutaneously injected in the flank of BALB/c mice. Once the mean tumors volume reached 115±30 mm3, tumors were intratumor injected with HfO2-NP and irradiated with 2Gyx3 or 4Gyx3, or irradiated only. Tumors were collected 5 days after the last RT fraction and analyzed for immune cell infiltrates by immunohistochemistry (2Gyx3 and 4Gyx3) and cytokines content by flow cytometry (2Gyx3). […]

Results: In mice bearing CT26 tumors, a marked increase of cytokines content and immune cell infiltrates was observed with HfO2-NP + 2Gyx3 when compared to RT alone. The tumor immune cell infiltrates were
further enhanced with HfO2-NP + 4Gyx3. In mice inoculated with 4T1 cells treated with HfO2-NP + 40Gy, a marked increase of immune cell infiltrate (CD8+) was observed in tumors when compared to tumors in mice inoculated with 4T1 cells treated with 40Gy and control.

Conclusions: These in vivo data generated from CT26 and 4T1 tumor models suggest that HfO2-NP + RT triggers immunogenic conversion of the tumor microenvironement when compared to RT alone. HfO2-NP treatment may represent a therapeutical approach for broad applications since it does not rely on any molecular characteristics of the tumor.

Summary

Background: Between 70 to 90% of patient have “cold” tumors, i.e. devoid or poorly infiltrated by immune cells, rendering inoperative their treatment by immune checkpoint inhibitors. To allow these patients to benefit from these therapies, it is fundamental to prime an antitumor immune response. Radiotherapy (RT) has demonstrated its ability to induce the immunogenic cell death (ICD), a crucial event allowing the priming of the antitumor immune response. Meanwhile, a new class of material with high electron density, hafnium oxide, was designed at the nanoscale (HfO2-NP) to efficiently absorb ionizing radiation and increase the radiation dose deposition from within the tumor cells and increase killing of cancer cells. Here, we compared the ability of HfO2-NP and RT to RT alone to kill cancer cells and induce immunogenic cell death.

Methods: A panel of human and mouse cancer cell lines (mesenchymal and epithelial origin, radiosensitive and radioresistant) were treated or not with HfO2-NP, then irradiated by X-rays. Impact of the treatments on apoptosis and necrosis was assessed by FACS analysis (Annexin V/Propidium iodide). […]

Results: For all the tested cell lines treated with HfO2-NP and RT, a marked increase of apoptosis and necrosis was demonstrated, compared to cells treated with RT alone. In addition, higher levels of DAMPs (ecto-CRT, ecto-HSP70, ecto-HSP90, secreted ATP and extracellular HMGB1) were measured in the cancer cells treated with HfO2-NP and RT when compared to cancer cells exposed to RT.

Conclusions: HfO2-NP has demonstrated its capacity to kill cancer cells more efficiently than radiotherapy alone. HfO2-NP, administered via a single intratumor injection, is currently evaluated in clinical trials including soft tissue sarcoma (phase II/III), head and neck, prostate, liver and rectum cancers (phase I) and would permit to improve the local control of tumors, a crucial parameter for the cure and survival of patients. […]

Summary

Background: Functionalized hafnium oxide nanoparticles (NBTXR3) have been developed as selective radioenhancers, which may represent a breakthrough approach for the local treatment of solid tumors. The high electron density of the nanoparticles, when exposed to radiotherapy (RT), allow the absorption/deposition of a high radiation dose within the tumor cells, to physically kill the cells and possibly improve outcome. A phase I trial was implemented for the treatment of locally advanced HNSCC in patients (pts) older than 65 years who cannot receive cisplatin.

Methods: Pts received a single intratumor (IT) injection of NBTXR3, volume dose levels escalated at 5%, 10%, 15% and 22% of baseline tumor volume, followed by RT (IMRT, 70Gy/ 35 fractions / 7 weeks). Primary endpoints included feasibility of the IT implantation and safety. Secondary endpoints included IT residency of NBTXR3 using CT scan and RECIST 1.1 response.

Results: Enrollment was completed for volume 5%, 10%, and 15% (11 pts) and 1 patient at volume dose level 22%. Feasibility of the IT injection was confirmed. The treatment was easily administered, was safe with no SAE, or early DLT, which allowed the pts for completion of the planned RT schedule. Adverse events related to the injection procedure included grade 1-2 injection pain (1 pt), and tumor hemorrhage (1 pt). Results demonstrated that a single injection of NBTXR3 provides adequate bioavailability of NBTXR3 IT over seven weeks of RT. No leakage of NBTXR3 to the adjoining healthy tissues was observed. Preliminary results of antitumor activity according to RECIST 1.1 are presented below: 11 evaluable pts, 10 showed complete or partial response (RECIST 1.1) including, 1/5 complete response at dose levels ≤ 10% and 3/6 complete responses at dose levels > 10% Follow up results with duration of response and tolerance will be disclosed.

Conclusions: Injection of NBTXR3 was safe and well tolerated. All pts received the planned RT.

Summary

Background: NBTXR3 are functionalized hafnium oxide nanoparticles, undergoing seven clinical trials for enhancing radiation therapy (RT). The high electron density of the nanoparticles, when exposed to radiotherapy (NBTXR3 + RT), allow absorption/deposition of a high radiation dose within the cancer cells to physically kill the cells, and possibly improve outcome. Besides, NBTXR3 + RT has shown subsequent ability to enhance immunogenic cell death and immune response in preclinics. We hypothesized that NBTXR3 + RT could trigger an enhanced immune response when compared to RT in patients with STS.

Methods: Tumor tissues pre- (biopsy) and/or post-treatment (resection) were collected from patients (pts) with locally advanced STS, who received either NBTXR3 as intratumor injection and RT (14 pts) or RT (12 pts), as preoperative treatment (NCT02379845). Immunohistochemistry and Digital Pathology for immune biomarkers and for Immunoscore (CD3/CD8) were analyzed. Gene expression profiling and pre-optimized immune-gene signatures called Immunosign were also used.

Results: A significant increase of T cells (CD3+, CD8+) and a marked increase of CD103+ immune cell infiltration post- vs pre-treatment were observed for NBTXR3 + RT (P< 0.01), while no differences were seen for RT. Post-treatment, an increased Immunoscore (CD3 + CD8 cell densities) was observed for NBTXR3 + RT compared to RT (P < 0.07). Consistently, the up-regulation of pan immune genes expression and specifically expression of adaptive immunity genes between pre- and post-treatment, was pronounced for NBTXR3 + RT when compared to RT. Functional analysis of genes up-regulated in NBTXR3 + RT showed an enrichment of cytokine activity (IL7, IFNA, IL16, IL11, IFNG), adaptive immunity (RAG1, GZMA, TAP1, TAP2, TBX21, STAT4, IFNG, LCK, LTK, CD37, CD22) and T cell receptor signaling pathway (CD28, CTLA4, CD274, BTLA, TIGIT, CD40LG, CD5, CD3E, ZAP70).

Conclusions: NBTXR3 + RT induces a specific adaptive immune pattern. As such, it may contribute to convert “cold” tumor into “hot” tumor and be effectively combined with immunotherapeutic agents across oncology. These data warrant more tissue samples evaluation to reinforce these findings.

Summary

Background: Functionalized hafnium oxide nanoparticles (NBTXR3) have been developed as selective radioenhancers, which may represent a breakthrough approach for the local treatment of solid tumors. This is a unique approach where crystalline nanomaterials with high electron density when exposed to radiotherapy, can allow penetrate into the cell and make feasible the absorption/deposition of a high energy dose within the tumor cell. A phase I/II trial was implemented in patients with locally advanced STS.

Methods: Patientsreceived a single intratumor (IT) injection of NBTXR3, volume escalated, followed by 50Gy RTx. Primary endpoints include feasibility of the IT implantation and safety. Secondary endpoints focus on efficacy such as pathological and RECIST response, IT residency of NBTXR3 over all the RTx period and operability. Results: Enrollment was completed for volume 1, 2, and 3 (15 pts). Feasibility of the IT injection was confirmed. The treatment was safe with no SAE, no early DLT and allowed the pts for completion of the planned RTx schedule. No grade 3-4 toxicity occurred, main grade 1-2 toxicities related to NBTXR3 were injection pain/reaction (4 pts), pyrexia (2 pts), abdominal pain (1 pt), pruritus (1 pt) and paresthesia (1 pt). Results demonstrated that a single injection of NBTXR3 provides adequate bioavailability of NBTXR3 IT over five weeks of radiotherapy. No leakage of NBTXR3 to the adjoining healthy tissues was observed. Further, NBTXR3 persistence was established by CT scan before surgery.

Conclusions: Injection of NBTXR3 was well tolerated. All pts received the planned radiotherapy (50 Gy/25 fractions/ 5 weeks) followed by wide surgical resection of the sarcoma. NBTXR3 with RTx showed a very good safety profile. Encouraging signs of antitumor activity were observed in different sarcoma subtypes, such as undifferentiated sarcoma, rhabdomyosarcoma, and synovial sarcoma, which constitutes a promising feature for this subset of pts whose primary tumor is locally advanced and has an important risk of relapse. Clinical trial information: NCT01433068.